This invention relates to antifriction bearing assemblies of the type referred to in U.S. Pat. No. 851,019 of Model, U.S. Pat. No. 860,186 of Beemer, U.S. Pat. No. 1,015,441 of Hess, U.S. Pat. No. 1,209,537 of Atkins, U.S. Pat. No. 3,208,806 of Grolmann et al. More particularly, the present invention provides improvements in structure as illustrated in U.S. Pat. No. 3,712,694 of Smith relating to antifriction bearing spacers of incompressible, lubricative material such as graphite.
Bearing spacers of the type described are normally disposed between the adjacent bearings in a bearing assembly,, such as adjacent steel ball bearings, and have concave end walls in which the ball bearings rotate. Such rotation of the ball bearings plus rotation of the bearing spacer between the inner and outer races of the bearing produces a lubricating film as the spacer wears.
Because of the relatively brittle nature of the material of which the bearing spacer is comprised, e.g., graphite, such spacers are subject to failure by cracking. Such phenomena has been discovered particularly at extremely high bearing speeds of approximately 25,000 rpm and high operating temperatures in the neighborhood of 900.degree. F.
While all the sources of forces which contribute to spacer breakage are not completely known, it is believed that this breakage is primarily due to vibration of the spacers. The primary vibration appears to be induced from the vibrations of the ball bearing members caused by their movement in a somewhat elliptical path about the center line of the races due to necessary manufacturing and machining tolerances. Such elliptical movement at high speeds creates vibration which, combined with the variable axial and radial loading imposed upon the ball bearings, tends to excite the spacer pellets into vibration.